Electromagnet with balanced armature



June 6, 1950 H. E. ASHWORTH 2, 0,

ELECTROMAGNET WITH BALANCED ARMATURE Filed Oct. 22, 1947 r 3 SheetsSheet1 Fig. 1. Fly. 5.

INVENTQR.

Harry Ash worlh BY H16 ATTORNEY June 6, 1950 ASHWQRTH 2,510,305

ELECTROMAGNET WITH BALANCED ARMATURE Filed Qct. 22, 1947 3 Sheets-Sheet2 Fig. 2.

INVENTORJ 11kg. Ash worth EIIS ATTORNEY June 6, 1950 H. E. ASHWORTH2,510,305

ELECTROMAGNET WITH BALANCED ARMATURE Filed Oct. 22, 1947 3 Sheets-Sheet3 I ll/lll/l/ll/Ill/"l1' '11 |mil6 m 21 17 20 7 j 3 5\ E 21 19 2 V 8 nI. 54 l m 2212 9 //1'///,///4'/L'/'/1 '/1 /4/////, III I. 1 1 5? 55 50 251 1 2511 Fly. 4.

IN! "EN TOR.

Harv A512 worth 5 V M 1115 A TTOHNEY Patented June 6, 1950 ELECTROMAGNETWITH BALANCED ARMATUBE Harry E. Ashworth, Penn Township, AlleghenyCounty, Pa., assignor to The Union Switch 8; Signal Company, Swissvale,Pa., a corporation of Pennsylvania Application October 22, 1947, SerialNo. 781,298

3 Claims. 1

My invention relates to electrical relays, and has particular relationto electrical relays having a centrally pivoted armature adapted to havethe opposite faces of its two ends simultaneously attracted to the facesof the pole pieces provided for the relay energizing magnet. Moreparticularly, my invention relates to an improved construction of arelay of this type.

Relays of the above described type have been proposed heretofore inorder to assure proper operation of the relay armature when subjected toshock and vibration, and to avoid chattering of the relay contacts atthe critical operating value of the relay current. These operatingcharacteristics are of prime importance in connection with apparatusmounted upon railway locomotives, such as, for example, train controlrelays which are subjected in service to extremely severe jars, shockand vibration.

An object of my invention is to provide a novel and improved relayadapted for use in applications where the relay is subjected to severeshock, jars and vibrations.

Another object is to provide a novel and improved relay having anarmature pivoted about its center to rotate in a vertical plane andarranged to have its opposite ends attracted simultaneously to the polefaces of the energizing magnet.

Another object is to provide a novel and improved construction of arelay having a centrally pivoted armature and incorporating means forestablishing and maintaining a predetermined relationship between thepole faces of the magnet pole pieces.

Another object is to improve the construction of relays having acentrally pivoted armature.

The above mentioned and other important objects and characteristicfeatures of my invention are attained in accordance with my invention byincorporating into a relay a supporting plate having means which locateand position the pole faces of the relay pole'pieces so as to establishand maintain a predetermined relationship between such faces, and byproviding in such a relay a novel arrangement of parts which cooperateto provide an improved and simplified manner of constructing the relay.

I shall describe one form of a relay embodying my invention and shallthen point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a front view of a novel andimproved relay embodying my invention. with the cover I! omitted. Fig. 2is right side view, partially sectional, of the relay shown in Fig. 1.Fig. 3 is a rear view of the relay shown in Fig. 1. Fig. 4 is a topview, partially sectional, of the relay shown in Fig. 1. Fig. 5 is asectional view taken on the line V-V of Fig. 1. In each of the severalviews. similar partshave been designated by corresponding referencecharacters.

- Referring to the drawings, a relay embodying my invention is shown ascomprising a frame I of suitable insulating material, such for example.as a phenol condensate product. A supporting plate 2 secured by screws 3to frame I is provided with a pair of circular openings 4 through whichproject cylindrical cores 5 integrally formed at their outer ends withenlarged pole pieces 6 (see Fig. 1) preferably rectangularly shaped. Thecores 5 are suitably threaded adjacent to the pole pieces 8 to receivecore nuts 6a which when tightened down secure cores 6 to plate 2 anddraw down pole pieces 6 into firm engagement with plate 2. Energizingwindings l are mounted on cores 5 which are connected together at theiropposite ends by a back strap 8 secured to the cores by bolts 9. Thewindings I are adapted to be supplied with current so as to constitutethe cores and windings of an electromagnet. The openings 4 in supportingplate 2 are located spaced apart in such a manner that with the faces ofpole pieces 6 arranged in predetermined relation to each other (as shownin Fig. 1), an armature l0 may be pivotally mounted intermediate itsends to lie between the pole pieces so that the opposite faces of thetwo ends of the armature will be simultaneously attracted to the polepieces 6. This arrangement is best shown in Fig. 1 in which it will beseen that when one face of one end of armature I0 is attracted to onepole piece 6 the opposite face of the other end of armature I 0 islikewise attracted to the other pole piece 6, the armature faces beingactually spaced away from contact with the pole pieces 6 by non-magneticcore pins ll carried by the armature and projecting slightly beyond thearmature face.

The armature I0 is pivotally supported about its center on pivots I2(see Fig. 5) carried in direct axial alignment in spaced aligned arms ofa bracket l3 fastened by bolts l3a to one of the pole pieces 6 carriedby plate 2. The bracket l3 also carries a pair of Springs H which engagethe opposite faces of armature III on opposite sides of its center, anda stop screw l5 which functions to limit the travel of armature Ill awayfrom the pole pieces 6. The springs M are adjustable by means of boltsl6 and function to impose forces on the armature tending to rotate it toa position away from the pole pieces so that when the windings I aredeenergized the armature is biased to and will assume the position awayfrom pole pieces 6, in which biased position the armature is in contactwith stop screw I5. When windings 1 are energized by current of suitablemagnitude, armature In will be attracted to the pole pieces 6 and willassume the position in which the armature is represented in thedrawings.

The armature I is provided at its extreme ends with driving members I!of insulating material secured at one end as by screws l8 to armature l0and operatively connected at the other end with movable contact fingersN by means of a transverse contact operating pin loosely mounted inmember H. The pins 20 are engaged by clips 2| secured to fingers l9 andfunction to drive the fingers i9 between two fixed contact fingers 22band 22 the fingers i9 engaging fingers 22b whenever armature I0 occupiesits biased position away from the pole pieces 6, and finger l9 engagingfinger 22f when armature Ill is attracted to pole pieces 6 bytheenergizaticn of windings l. The contact operating structure described isin general similar to that shown and claimed in Letters Patent of theUnited States No. 2,347,834, granted on May 2, 1944, to John W.Livingston. I

As can be seen in the drawings, groups of fingers each including fingersi9, 22b and 22] arranged in alignment, are provided and preferably twoof such groups of contacts (see Fig. 2) are provided for each drivingmember H. Each group of three fingers includes a movable contact finger19 located between a cooperating back contact finger 22b and acooperating front contact finger 22 The forward portion of each fingeris flexible and is riveted to a rigid rear portion 28 moulded into aninsulating block 24. Two of the insulating blocks 24 as shown supportthe two rows of three fingers each provided for each contact operatingpin 20, and each block is removably clamped by means of screws 25against the forward face of frame member l'so that the contacts may bereadily removed and replaced with other contacts when desired. The rigidportion of each contact finger 23 is made suificiently long to extendthrough an aligned opening in the frame member i into a rectangularrecess formed in the rear side of frame member 8, and these rigidportions of the contact fingers 23 constitute a plug for making contactswith a suitable female connector in the manner described in detail inLetters Patent No. 2,198,704, granted on April 30, 1940, to BrankoLazich. As shown in Fig. 4, an extra set of fingers 23a may be providedin frame i so as to be entirely independent of the fingers 23 carried bycontact blocks 24. The fingers 23a are preferably provided to constituteterminals for establishing connection between coils I and the terminalsof the mating female connectors.

The armature and contact assembly previously described is suitablyenclosed preferably by a transparent cover composed of glass or plastic,which fits in a rubber gasket 3! and is held attached to frame I bymeans of nuts 32 which are threaded onto hollow externally threadedtubes 33 (see Fig. 4) moulded into frame I. As shown in Fig. 2, a pullmember 34 is confined between cover 30 and nuts 32 and is formed withwings adapted to be grasped so as to make the. relay readily capable ofbeing plugged in or detached from its cooperating female connector. Itshould be noted that the hollow tubes 33 may constitute 70 guidesthrough which rods (not shown) provided on the female connector mayproject outwardly beyond the cover. It is contemplated that these rodswill be threaded at their outer ends to receive nuts which whentightened down attach the relay to the mating female connector.

It will be noted from an inspection of the drawings that the pivots l2are located in alignment in such a manner that armature ID will rotateabout a horizontal axis in a vertical plane. Also, it will be noted thatthe facesof the pole pieces 6 are disposed at an angle with respect toboth the horizontal and vertical axis of the relay so that with thecorresponding faces of the two pole pieces 6 in parallel relationship,the armature ill will also operate at an angle with the horizontal andvertical axis of the relay. The parts of the relay armature are soproportioned that when the armature is in its mid-stroke position, thatis, when the armature is half-way between its fully attracted positionwhen the core pins ll engage the faces of the pole pieces 6, and itsfully released position in which armature I I! engages stop screw 45,the transverse pins 20 carried at the opposite ends of armature iii arethen directly in alignment with the pivots i2 and these members will alllie in the vertical axis of the relay. At this position of the parts,the plane including the pivots i2 and contact operating pins 20 isperpendicular to the line of motion of the movable contact fingers i9with the result that the arc traversed by each contact operating pin 20is tangent to line of operation of the movable contact finger H) t themid-stroke position of arma ture in.

The amount of motion given to the contact operating pin 20 by movementof driving member If, attached to armature ill, is relatively limited asis readily apparent from an inspection of the drawing, and as a resultthe motion of driving member ii is substantially in the same plane asthat defined by the motion of the center of the contact spring operatingpins 20.

The parts of the contact assembly and armature are so arranged thatsubstantially a balanced armature type relay is provided. That is tosay, all of the contact operating arm's, contact loads, biasing springforces, etc., imposed upon the armature in are balanced about the centerpivots i2 so that a symmetrical arrangement is provided which tendstomake the armature immune to vibration and shock. In other words, ifthe armature I0 is in its released position, shock or vibration actingupon the armature will not cause the armature to rotate about the pivotl2 due to its stable condition of equilibrium. The same condition istrue when the armature is energized, and it will be noted that when thearmature is picked up it is held attracted by a force couple operatingon the armature on opposite sides of the armature pivot mounting.

In providing a relay of the type hereinbefore described, it is essentialthat the faces of the pole pieces 6 be held in a predeterminedrelationship with each other in order to provide for proper cooperationwith the opposite ends of the pivotally mounted armature I0. For ease inmanufacturing and assembly, the cores 5 preferably are formed ofcylindrical material which is upset at one end to provide arectangularly formed pole piece 6. The openings 4 in the supportingplate 2 are circular in shape to permit insertion of the cores, so thatthese openings provide no means for establishing the predeterminedrelationship between the faces of the pole pieces 6. This relationshipis established however in accordance with my invention by providingsidewalls 35 in the supporting member 2. These sidewalls 35 are formedby milling or slotting depressions in the supporting member 2, with thesides of the depressions running parallel to each other to form acentral rib (see Fig. 5) whose sides engage the faces of the pole pieces6. In assembling the parts, therefore, the cylindrical cores 5 areinserted through the holes 4 and the faces of the pole pieces 6 are thenbrought into alignment with the side walls 35 so that the pole pieces 6can be forced down firmly into engagement with the side walls 35. Thecores are fastened to supporting plate 2 by core nuts 6a, which insurethat the pole pieces 6 are held in contact with the sidewalls formingthe central rib to maintain the established relationship of the faces ofthe pole pieces 6 with respect to each other, and to readily permitassembly of the parts of the relay.

An additional feature of my invention is the provision of an armatureassembly comprising the armature l0, its supporting pivots l2, biasingsprings I4 and armature stop [5 all mounted on the armature bracket l3.The pivots l2, armature I0, springs l4 and stop [5 are first assembledon bracket [3 as a unit, and that unit is then secured to one of thepole pieces which has been prepared with drilled openings to receive thebolts I3a which attach the bracket Hi to the pole piece. Preferably, thebracket I3 is further secured to its pole piece 6 by dowel pins (notshown) driven through the bracket member into the pole piece. This polepiece 6 is of course accurately positioned with respect to the otherpole piece by the rib of supporting plate 2, so that the armatureassembly when mounted on the one pole piece accurately positions thearmature l0 relative to both of its cooperating pole pieces, with thearmature pivots, biasing springs and stop arranged in proper relation tothe armature. This arrangement therefore aifords a convenient andsimplified manner of assembly of the components in the relay structure.

Although I have herein shown and described only one form of anelectrical relay embodying my invention, it is understood that variouschanges and modifications may be made therein within the scope of theappended claims without departing from the spirit and scope of myinvention.

Having thus described my invention, what I claim is:

1. In a relay, in combination, a supporting plate provided with a riband with a pair of openings disposed respectively on opposite sides ofsaid rib, a pair of cores one extending through each of said openingsand each provided with an enlarged pole piece engaging said rib, meanssecuring said cores to said supporting plate in such manner that saidpole pieces are maintained in predetermined relative positions byengagement with said rib, and a removable armature assembly secured as aunit to one of said pole pieces, said armature assembly comprising abracket member separate from said supporting plate, a pair of pivot pinsmounted in alignment in said bracket member, an armature pivotallymounted on said pivot pins intermediate its ends for movement toward andaway from both said pole pieces, and spring means secured to saidbracket member and engaging said armature to bias said armature awayfrom said pole pieces.

2. In a relay, in combination, a supporting plate provided with a riband with a pair of open ings disposed respectively on opposite sides ofsaid rib, a pair of cores one extending through each of said openingsand each provided with an enlarged pole piece engaging said rib, meanssecuring said cores to said supporting plate in such manner that saidpole pieces are maintained in predetermined relative positions byengagement with said rib, and a removable armature assembly secured as aunit to one of said pole pieces, said armature assembly comprising abracket member separate from said supporting plate, a pair of pivot pinsmounted in alignment in said bracket member, an armature pivotallymounted on said pivot pins intermediate its ends for movement toward andaway from both said pole pieces, spring means secured to said bracketmember and engaging said armature to bias said armature away from saidpole pieces, and a stop secured to said bracket member and cooperatingwith said armature to limit its movement due to said biasing springs.

3. In a relay, in combination, a supporting plate provided with a riband with a pair of openings disposed respectively on opposite sides ofsaid rib, a pair of cores one extending through each of said openingsand each provided with an enlarged pole piece engaging said rib, corenuts securing said cores to said supporting plate in such manner thatsaid pole pieces are maintained in predetermined relative positions byengagement with said rib, a removable armature assembly comprising abracket member separate from said supporting plate, a pair of pivot pinsmounted in alignment in said bracket member, an armature pivotallymounted intermediate its ends on said pivot pins, and spring meanssecured to said bracket member and engaging opposite sides of saidarmature on opposite sides of its pivotal axis; and means securing saidarmature assembly as a unit to one oi. said pole pieces for positioningsaid armature in cooperating relation to bth said pole pieces with saidaligned pivots located between said pole pieces.

HARRY E. ASHWORTH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 539,123 Eckert May 14, 18951,696,170 Leake Dec. 18, 1928 1,763,003 Mead June 10, 1930 2,120,339Mishelevich June 14, 1938 2,360,664 Field Oct. 17, 1944

